The dried bark of Rhamnus Purshianus. North Pacific Coast.

Characters. - In quills or incurved pieces of varying lengths and sizes, the bark itself being from about 1/25 to 1/8 of an inch thick, smooth or nearly so externally, covered with a greyish-white layer, which is usually easily removed, and frequently marked with spots or patches of adherent lichens. Beneath the surface it is violet-brown, reddish-brown, or brownish; and internally reddish-brown or yellowish-brown, and nearly smooth, although somewhat striated longitudinally. Fracture short, except internally, where it is slightly fibrous, more especially in the larger pieces. No marked odour; taste bitter. It is frequently imported in flattened packets, consisting of small pieces of the bark compressed into a more or less compact mass.

Composition. - Cascara bark contains several resinoid bodies, which are supposed to be derived from chrysophanic acid. It also contains much tannin.

Action and Uses. - All the species of buckthorn appear to possess cathartic properties. Cascara Sagrada is usually given in the form of liquid extract in doses of 1/2 to 1 fl. dr., but 1/2 fl. dr. or less given immediately after rising in the morning or at bedtime is often sufficient. It may also be given with advantage in chronic constipation in doses of 10-15 min. thrice a day before meals. It acts as a stomachic tonic and bitter in these small doses.